Performance optimization: defer attempt to use user-defined conversions during overload resolution, bug 268383.

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPSemantics.java

@@ -175,6 +175,7 @@ import org.eclipse.cdt.internal.core.dom.parser.cpp.ICPPInternalUnknownScope;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.ICPPUnknownBinding;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.ICPPUnknownType;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.OverloadableOperator;
+import org.eclipse.cdt.internal.core.dom.parser.cpp.semantics.Conversions.UDCMode;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.semantics.Cost.Rank;
 import org.eclipse.cdt.internal.core.index.IIndexScope;
 
@@ -2116,7 +2117,9 @@ public class CPPSemantics {
 		boolean ambiguous = false;				// ambiguity, 2 functions are equally good
 		FunctionCost bestFnCost = null;		    // the cost of the best function
 				
+		
 		// Loop over all functions
+		List<FunctionCost> potentialCosts= null;
 		for (IFunction fn : fns) {
 			if (fn == null) 
 				continue;
@@ -2131,6 +2134,13 @@ public class CPPSemantics {
 				return CPPUnknownFunction.createForSample(firstViable, data.astName);
 			}
 
+			if (fnCost.hasDeferredUDC()) {
+				if (potentialCosts == null) {
+					potentialCosts= new ArrayList<FunctionCost>();
+				}
+				potentialCosts.add(fnCost);
+				continue;
+			}
 			int cmp= fnCost.compareTo(data, bestFnCost);
 			if (cmp < 0) {
 				bestFnCost= fnCost;
@@ -2140,6 +2150,20 @@ public class CPPSemantics {
 			}
 		}
 		
+		if (potentialCosts != null) {
+			for (FunctionCost fnCost : potentialCosts) {
+				if (!fnCost.mustBeWorse(bestFnCost) && fnCost.performUDC()) {
+					int cmp= fnCost.compareTo(data, bestFnCost);
+					if (cmp < 0) {
+						bestFnCost= fnCost;
+						ambiguous= false;
+					} else if (cmp == 0) {
+						ambiguous= true;
+					}
+				}
+			}
+		}
+
 		if (bestFnCost == null)
 			return null;
 		
@@ -2186,7 +2210,7 @@ public class CPPSemantics {
 			} else {
 			    if (CPPTemplates.isDependentType(implicitType))
 			    	return CONTAINS_DEPENDENT_TYPES;
-				cost = Conversions.checkImplicitConversionSequence(null, thisType, implicitType, false, true);
+				cost = Conversions.checkImplicitConversionSequence(null, thisType, implicitType, UDCMode.noUDC, true);
 			}
 			if (cost.getRank() == Rank.NO_MATCH)
 				return null;
@@ -2194,6 +2218,7 @@ public class CPPSemantics {
 			result.setCost(k++, cost);
 		}
 
+		final UDCMode udc = allowUDC ? UDCMode.deferUDC : UDCMode.noUDC;
 		for (int j = 0; j < sourceLen; j++) {
 			final IType argType= argTypes[j];
 			if (argType == null)
@@ -2217,7 +2242,7 @@ public class CPPSemantics {
 			} else {
 			    if (CPPTemplates.isDependentType(paramType))
 			    	return CONTAINS_DEPENDENT_TYPES;
-				cost = Conversions.checkImplicitConversionSequence(arg, argType, paramType, allowUDC, false);
+				cost = Conversions.checkImplicitConversionSequence(arg, argType, paramType, udc, false);
 			}
 			if (cost.getRank() == Rank.NO_MATCH)
 				return null;

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/Conversions.java

@@ -51,21 +51,24 @@ import org.eclipse.core.runtime.CoreException;
  * Routines for calculating the cost of conversions.
  */
 public class Conversions {
+	enum UDCMode {allowUDC, noUDC, deferUDC}
 	/**
 	 * Computes the cost of an implicit conversion sequence
 	 * [over.best.ics] 13.3.3.1
 	 * @param sourceExp the expression behind the source type
 	 * @param source the source (argument) type
 	 * @param target the target (parameter) type
-	 * @param allowUDC whether a user-defined conversion is allowed during the sequence
 	 * @param isImpliedObject
 	 * 
 	 * @return the cost of converting from source to target
 	 * @throws DOMException
 	 */
 	public static Cost checkImplicitConversionSequence(IASTExpression sourceExp, IType source,
-			IType target, boolean allowUDC, boolean isImpliedObject) throws DOMException {
-		allowUDC &= !isImpliedObject;
+			IType target, UDCMode udc, boolean isImpliedObject) throws DOMException {
+		if (isImpliedObject) {
+			udc= UDCMode.noUDC;
+		}
+		
 		target= getNestedType(target, TDEF);
 		source= getNestedType(source, TDEF);
 		
@@ -92,7 +95,7 @@ public class Conversions {
 				} 
 			}
 			
-			if (T2 instanceof ICPPClassType && allowUDC) {
+			if (T2 instanceof ICPPClassType && udc != UDCMode.noUDC) {
 				// Or has a class type (i.e., T2 is a class type) and can be implicitly converted to
 				// an lvalue of type "cv3 T3," where "cv1 T1" is reference-compatible with "cv3 T3" 92)
 				// (this conversion is selected by enumerating the applicable conversion functions
@@ -107,7 +110,7 @@ public class Conversions {
 							IType cvT2= getNestedType(newSource, TDEF | REF);
 							Cost cost2= isReferenceCompatible(cv1T1, cvT2, false); 
 							if (cost2 != null) {
-								int cmp= cost2.compare(operatorCost);
+								int cmp= cost2.compareTo(operatorCost);
 								if (cmp <= 0) {
 									ambiguousConversionOperator= cmp == 0;
 									operatorCost= cost2;
@@ -150,7 +153,7 @@ public class Conversions {
 
 					// We must do a non-reference initialization
 					if (!illformed) {
-						return nonReferenceConversion(source, cv1T1, allowUDC, isImpliedObject);
+						return nonReferenceConversion(source, cv1T1, udc, isImpliedObject);
 					}
 				}
 			}
@@ -158,18 +161,18 @@ public class Conversions {
 		} 
 		
 		// Non-reference binding
-		return nonReferenceConversion(source, target, allowUDC, isImpliedObject);
+		return nonReferenceConversion(source, target, udc, isImpliedObject);
 	}
 
-	private static Cost nonReferenceConversion(IType source, IType target, boolean allowUDC,
-			boolean isImpliedObject) throws DOMException {
+	private static Cost nonReferenceConversion(IType source, IType target, UDCMode udc, boolean isImpliedObject) throws DOMException {
 		Cost cost= checkStandardConversionSequence(source, target, isImpliedObject);
-		if (allowUDC && cost.getRank() == Rank.NO_MATCH) { 
-			Cost temp = checkUserDefinedConversionSequence(source, target);
+		if (cost.getRank() != Rank.NO_MATCH || udc == UDCMode.noUDC) 
+			return cost;
+		
+		Cost temp = checkUserDefinedConversionSequence(source, target, udc == UDCMode.deferUDC);
 		if (temp != null) {
 			cost = temp;
 		}
-		}
 		return cost;
 	}
 
@@ -318,13 +321,23 @@ public class Conversions {
 	 * @return
 	 * @throws DOMException
 	 */
-	private static final Cost checkUserDefinedConversionSequence(IType source, IType target) throws DOMException {
+	static final Cost checkUserDefinedConversionSequence(IType source, IType target, boolean deferUDC) throws DOMException {
 		Cost constructorCost= null;
 		Cost operatorCost= null;
 
 		IType s= getNestedType(source, TDEF | CVQ | REF);
 		IType t= getNestedType(target, TDEF | CVQ | REF);
 
+		if (!(s instanceof ICPPClassType || t instanceof ICPPClassType)) {
+			return null;
+		}
+		
+		if (deferUDC) {
+			Cost c= new Cost(s, t, Rank.USER_DEFINED_CONVERSION);
+			c.setDeferredUDC(true);
+			return c;
+		}
+		
 		//constructors
 		if (t instanceof ICPPClassType) {
 			ICPPConstructor[] ctors= ((ICPPClassType) t).getConstructors();
@@ -359,7 +372,7 @@ public class Conversions {
 				for (final ICPPMethod op : ops) {
 					Cost cost= checkStandardConversionSequence(op.getType().getReturnType(), target, false);
 					if (cost.getRank() != Rank.NO_MATCH) {
-						int cmp= cost.compare(operatorCost);
+						int cmp= cost.compareTo(operatorCost);
 						if (cmp <= 0) {
 							cost.setUserDefinedConversion(op);
 							operatorCost= cost;
@@ -373,13 +386,13 @@ public class Conversions {
 		if (constructorCost != null) {
 			if (operatorCost != null && !ambiguousConversionOperator) {
 				// If both are valid, then the conversion is ambiguous
-				constructorCost.setAmbiguousUserdefinedConversion(true);
+				constructorCost.setAmbiguousUDC(true);
 			} 
 			return constructorCost;
 		} 
 		
 		if (operatorCost != null) {
-			operatorCost.setAmbiguousUserdefinedConversion(ambiguousConversionOperator);
+			operatorCost.setAmbiguousUDC(ambiguousConversionOperator);
 			return operatorCost;
 		}
 

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/Cost.java

@@ -13,7 +13,6 @@
  *******************************************************************************/
 package org.eclipse.cdt.internal.core.dom.parser.cpp.semantics;
 
-import org.eclipse.cdt.core.dom.ast.DOMException;
 import org.eclipse.cdt.core.dom.ast.IType;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPFunction;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPMethod;
@@ -34,7 +33,8 @@ final class Cost {
 
 	private Rank fRank;
 	private Rank fSecondStandardConversionRank;
-	private boolean fAmbiguousUserdefinedConversion;
+	private boolean fAmbiguousUDC;
+	private boolean fDeferredUDC;
 	private int fQualificationAdjustments;
 	private int fInheritanceDistance;
 	private ICPPFunction fUserDefinedConversion;
@@ -53,12 +53,20 @@ final class Cost {
 		fRank= rank;
 	}
 	
-	public boolean isAmbiguousUserdefinedConversion() {
-		return fAmbiguousUserdefinedConversion;
+	public boolean isAmbiguousUDC() {
+		return fAmbiguousUDC;
 	}
 
-	public void setAmbiguousUserdefinedConversion(boolean val) {
-		fAmbiguousUserdefinedConversion= val;
+	public void setAmbiguousUDC(boolean val) {
+		fAmbiguousUDC= val;
+	}
+
+	public boolean isDeferredUDC() {
+		return fDeferredUDC;
+	}
+
+	public void setDeferredUDC(boolean val) {
+		fDeferredUDC= val;
 	}
 
 	public int getInheritanceDistance() {
@@ -93,10 +101,13 @@ final class Cost {
 	 *        0 if this cost is equal to the other cost,
 	 *        an integer &gt 0 if this cost is larger than the other cost.
 	 */
-	public int compare(Cost other) throws DOMException {
+	public int compareTo(Cost other) {
 		if (other == null)
 			return -1;
 		
+		// cannot compare costs with deferred user defined conversions
+		assert !fDeferredUDC && !other.fDeferredUDC;
+
 		int cmp= fRank.compareTo(other.fRank);
 		if (cmp != 0) 
 			return cmp;
@@ -104,7 +115,7 @@ final class Cost {
 		// rank is equal
 		if (fRank == Rank.USER_DEFINED_CONVERSION) {
 			// 13.3.3.1.10
-			if (isAmbiguousUserdefinedConversion() || other.isAmbiguousUserdefinedConversion())
+			if (isAmbiguousUDC() || other.isAmbiguousUDC())
 				return 0;
 			
 			if (!fUserDefinedConversion.equals(other.fUserDefinedConversion))

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/FunctionCost.java

@@ -47,12 +47,34 @@ class FunctionCost {
 	
 	public boolean hasAmbiguousUserDefinedConversion() {
 		for (Cost cost : fCosts) {
-			if (cost.isAmbiguousUserdefinedConversion())
+			if (cost.isAmbiguousUDC())
 				return true;
 		}
 		return false;
 	}
 
+	public boolean hasDeferredUDC() {
+		for (Cost cost : fCosts) {
+			if (cost.isDeferredUDC())
+				return true;
+		}
+		return false;
+	}
+	
+	public boolean performUDC() throws DOMException {
+		for (int i = 0; i < fCosts.length; i++) {
+			Cost cost = fCosts[i];
+			if (cost.isDeferredUDC()) {
+				Cost udcCost= Conversions.checkUserDefinedConversionSequence(cost.source, cost.target, false);
+				if (udcCost == null) {
+					return false;
+				}
+				fCosts[i]= udcCost;
+			}
+		}
+		return true;
+	}
+
 	/**
 	 * Compares this function call cost to another one.
 	 */
@@ -75,7 +97,7 @@ class FunctionCost {
 				break;
 			}
 
-			int cmp = cost.compare(other.getCost(idxOther));
+			int cmp = cost.compareTo(other.getCost(idxOther));
 			haveWorse |= (cmp > 0);
 			haveBetter |= (cmp < 0);
 		}
@@ -113,6 +135,36 @@ class FunctionCost {
 		return 1;
 	}
 	
+	public boolean mustBeWorse(FunctionCost other) {
+		if (other == null)
+			return false;
+		
+		boolean haveWorse= false;
+		int idx= getLength()-1;
+		int idxOther= other.getLength()-1;
+		for (; idx>=0 && idxOther>=0; idx--,idxOther--) {
+			Cost cost= getCost(idx);
+			if (cost.getRank() == Rank.NO_MATCH) 
+				return true;
+			
+			Cost otherCost= other.getCost(idxOther);
+			
+			int cmp;
+			if (cost.isDeferredUDC()) {
+				cmp= cost.getRank().compareTo(otherCost.getRank());
+			} else {
+				cmp= cost.compareTo(otherCost);
+			}
+			
+			if (cmp < 0)
+				return false;
+			if (cmp > 0)
+				haveWorse= true;
+		}
+		
+		return haveWorse;
+	}
+
 	private static ICPPFunctionTemplate asTemplate(IFunction function) {
 		if (function instanceof ICPPSpecialization) {
 			IBinding original= ((ICPPSpecialization) function).getSpecializedBinding();